This invention is related to the field of organometal catalyst compositions.
The production of polymers is a multi-billion dollar business. This business produces billions of pounds of polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
One of these technologies is called metallocene catalyst technology. Metallocene catalysts have been known since about 1960. However, their low productivity did not allow them to be commercialized. About 1975, it was discovered that contacting one part water with two parts trimethylaluminum to form methyl aluminoxane, and then contacting such methyl aluminoxane with a metallocene compound, formed a metallocene catalyst that had greater activity. However, it was soon realized that large amounts of expensive methyl aluminoxane were needed to form an active metallocene catalyst. This has been a significant impediment to the commercialization of metallocene catalysts.
Borate compounds have been used in place of large amounts of methyl aluminoxane. However, this is not satisfactory, since borate compounds are very sensitive to poisons and decomposition, and can also be very expensive.
It should also be noted that having a heterogeneous catalyst is important. This is because heterogeneous catalysts are required for most modem commercial polymerization processes. Furthermore, heterogeneous catalysts can lead to the formation of substantially uniform polymer particles that have a high bulk density. These types of substantially uniformed particles are desirable because they improve the efficiency of polymer production and transportation. Efforts have been made to produce heterogeneous metallocene catalysts; however, these catalysts have not been entirely satisfactory.
Therefore, there is a need in the polymer industry to provide an economic material to activate metallocene catalysts, and there is also a need for efficient heterogeneous metallocene catalysts. The inventors provide this invention to help solve these problems.
An object of this invention is to provide a process that produces a catalyst composition that can be used to polymerize at least one monomer to produce a polymer.
Another object of this invention is to provide the catalyst composition.
Another object of this invention is to provide a process comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce the polymer.
Another object of this invention is to provide an article that comprises the polymer produced with the catalyst composition of this invention.
In accordance with one embodiment of this invention, a process to produce a catalyst composition is provided. The process comprises (or optionally, xe2x80x9cconsists essentially ofxe2x80x9d, or xe2x80x9cconsists ofxe2x80x9d) contacting an organometal compound, an organoaluminum compound, and a fluorided solid oxide compound;
wherein said organometal compound has the following general formula:
(X1)(X2)(X3)(X4)M1
wherein M1 is selected from the group consisting of titanium, zirconium, and hafnium;
wherein (X1) is independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls;
wherein substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X1) can be a bridging group which connects (X1) and (X2);
wherein (X3) and (X4) are independently selected from the group consisting of halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein (X2) is selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, substituted fluorenyls, halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein substituents on (X2) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X2) can be a bridging group which connects (X1) and (X2);
wherein the organoaluminum compound has the following general formula:
Al(X5)n(X6)3xe2x88x92n
wherein (X5) is a hydrocarbyl having from 1 to about 20 carbon atoms;
wherein (X6) is a halide, hydride, or alkoxide; and
wherein xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive;
wherein the fluorided solid oxide compound comprises fluoride and a solid oxide compound;
wherein the solid oxide compound is selected from the group consisting of silica-titania and silica zirconia.
In accordance with another embodiment of this invention, a process is provided comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce a polymer.
In accordance with another embodiment of this invention, an article is provided. The article comprises the polymer produced in accordance with this invention.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
Organometal compounds used in this invention have the following general formula:
(X1)(X2)(X3)(X4)M1
In this formula, M1 is selected from the group consisting of titanium, zirconium, and hafnium. Currently, it is most preferred when M1 is zirconium.
In this formula, (X1) is independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-Ixe2x80x9d) cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, such as, for example, tetrahydroindenyls, and substituted fluorenyls, such as, for example, octahydrofluorenyls.
Substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) can be selected independently from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Substituted silyl groups include, but are not limited to, alkylsilyl groups where each alkyl group contains from 1 to about 12 carbon atoms, arylsilyl groups, and arylalkylsilyl groups. Suitable alkyl halide groups have alkyl groups with 1 to about 12 carbon atoms. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Suitable examples of such substituents are methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloro, bromo, iodo, trimethylsilyl, and phenyloctylsilyl.
In this formula, (X3) and (X4) are independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-IIxe2x80x9d) halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Currently, it is preferred when (X3) and (X4) are selected from the group consisting of halides and hydrocarbyls, where such hydrocarbyls have from 1 to about 10 carbon atoms. However, it is most preferred when (X3) and (X4) are selected from the group consisting of fluoro, chloro, and methyl.
In this formula, (X2) can be selected from either Group OMC-I or Group OMC-II.
At least one substituent on (X1) or (X2) can be a bridging group that connects (X1) and (X2), as long as the bridging group does not substantially, and adversely, affect the activity of the catalyst composition. Suitable bridging groups include, but are not limited to, aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, phosphorous groups, nitrogen groups, organometallic groups, silicon, phosphorus, boron, and germanium.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Various processes are known to make these organometal compounds. See, for example, U.S. Pat. Nos. 4,939,217; 5,210,352; 5,436,305; 5,401,817; 5,631,335, 5,571,880; 5,191,132; 5,480,848; 5,399,636; 5,565,592; 5,347,026; 5,594,078; 5,498,581; 5,496,781; 5,563,284; 5,554,795; 5,420,320; 5,451,649; 5,541,272; 5,705,478; 5,631,203; 5,654,454; 5,705,579; and 5,668,230; the entire disclosures of which are hereby incorporated by reference.
Specific examples of such organometal compounds are as follows: 
Organoaluminum compounds have the following general formula:
Al(X5)n(X6)3xe2x88x92n
In this formula, (X5) is a hydrocarbyl having from 1 to about 20 carbon atoms. Currently, it is preferred when (X5) is an alkyl having from 1 to 10 carbon atoms. However, it is most preferred when (X5) is selected from the group consisting of methyl, ethyl, propyl, butyl, and isobutyl.
In this formula, (X6) is a halide, hydride, or alkoxide. Currently, it is preferred when (X6) is independently selected from the group consisting of fluoro and chloro. However, it is most preferred when (X6) is chloro.
In this formula, xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive. However, it is preferred when xe2x80x9cnxe2x80x9d is 3.
Examples of such compounds are as follows:
trimethylaluminum;
triethylaluminum (TEA);
tripropylaluminum;
diethylaluminum ethoxide;
tributylaluminum;
triisobutylaluminum hydride;
triisobutylaluminum;
diisobutylaluminum hydride; and
diethylaluminum chloride.
Currently, TEA is preferred.
The fluorided solid oxide compound comprises fluoride and a solid oxide compound. The solid oxide compound is selected from the group consisting of silica-titania and silica-zirconia. Silica is the majority component of the solid oxide compound.
The titania content of the silica-titania generally ranges from about 0.5% to about 30% by weight titanium, preferably, from about 2.5% to about 15% by weight titanium, and most preferably, from 4 to 10% by weight titanium.
The zirconia content of the silica-zirconia generally ranges from about 1% to about 40% by weight zirconium, preferably, from about 5% to about 30% by weight zirconium, and most preferably, from 8 to 20% by weight zirconium.
The solid oxide compound should have a pore volume greater than about 0.5 cc/g, preferably greater than about 0.8 cc/g, and most preferably, greater than 1 cc/g.
The solid oxide compound should have a surface area from about 100 m2/g to about 1000 m2/g, preferably from about 200 m2/g to about 800 m2/g, and most preferably, from 200 m2/g to 800 m2/g.
The solid oxide compound can be made by any method known in the art. In a first method, the solid oxide compound can be made by cogellation of aqueous materials, as represented in U.S. Pat. Nos. 3,887,494; 3,119,569; 4,405,501; 4,436,882; 4,436,883; 4,392,990; 4,081,407; 4,981,831; and 4,152,503; the entire disclosures of which are hereby incorporated by reference. In this procedure, a titanium or zirconium salt, such as titanyl sulfate, is dissolved in an acid, such as sulfuric acid, to which sodium silicate is added until gellation occurs at neutral pH. Aging for several hours at about pH 7 to 10 and at about 60 to about 90xc2x0 C. is followed by washing and drying. Drying may be accomplished by any means known in the art, such as, for example, azeotropic distillation, spray drying, flash drying, vacuum drying, and the like.
In a second method, the solid oxide compound can be made by cogellation in an organic or anhydrous solution as represented by U.S. Pat. Nos. 4,301,034; 4,547,557; and 4,339,559; the entire disclosures of which are hereby incorporated by reference. By these techniques, an organic silicate, such as, for example, tetraethyl orthosilicate, and an organic titanate or organic zirconate, such as, for example, titanium or zirconium tetraisopropoxide, is dissolved in an organic solution, such as, for example, an alcohol, to which a small amount of water is added along with an acid or base to cause hydrolysis and gellation of the solid oxide compound. The order of introduction of these ingredients can be varied, and the addition of each can be divided into stages to achieve special properties. Aging and drying often result in a high porosity solid oxide compound.
In a third method, the solid oxide compound can be made by coating the surface of silica with a layer of titania or zirconia, as exemplified by U.S. Pat. Nos. 4,424,320; 4,405,768; 4,402,864; 4,382,022; 4,368,303; and 4,294,724; the entire disclosures of which are hereby incorporated by reference. Any technique known in the art can be used. One particularly common method is to treat a silica, which has been dried at about 200xc2x0 C. to remove adsorbed water, with an organic solution of a titanium or zirconium alkoxide, such as, for example, titanium isopropoxide, or a titanium or zirconium halide, such as, for example, titanium tetrachloride. Subsequent drying and calcining in air at high temperature converts the titanium or zirconium into titania or zirconia, which remains substantially dispersed. This reaction can also be accomplished in a gas phase if the titanium or zirconium compound is vaporized into a gas stream which is then allowed to contact the silica.
Any method known in the art for fluoriding the solid oxide compound with a fluoride-containing compound can be used in this invention. One common way is to impregnate the solid oxide compound with an aqueous solution of a fluoride-containing salt, such as, for example, ammonium fluoride (NH4F), ammonium bifluoride (NH4HF2), hydrofluoric acid (HF), ammonium silicofluoride ((NH4)2SiF6), ammonium fluoroborate (NH4BF4), ammonium fluorophosphate (NH1PF6), fluoroboric acid (HBF4), and mixtures thereof. Alternatively, the fluoride-containing compound can be dissolved into an organic solvent, such as an alcohol, and used to impregnate the solid oxide compound to minimize shrinkage of pores during drying. Drying can be accomplished by any method known in the art such as vacuum drying, spray drying, flash drying, and the like.
The fluoride-containing compound can also be incorporated into a gel by adding it to one of the aqueous materials before gellation. These aqueous materials were disclosed in the first and second methods for preparing solid oxide compounds discussed previously in this disclosure.
The fluoride-containing compound can also be added to a slurry containing a gel before drying. Formation of a gel was disclosed in the first and second methods for preparing solid oxide compounds discussed previously in this disclosure.
The fluoride-containing compound can also be added during calcining. In this technique, the fluoride-containing compound is vaporized into a gas stream used to fluidize the solid oxide compound so that it is fluorided from the gas stream. In addition to some of the fluoride-containing compounds described above, volatile organic fluorides may be used at temperatures above their decomposition points, or at temperatures high enough to cause reaction. For example, perfluorohexane, perfluorobenzene, trifluoroacetic acid, trifluoroacetic anhydride, hexafluoroacetylacetonate, and the like may be vaporized and contacted with the solid oxide compound at about 300 to about 600xc2x0 C. in air or nitrogen. Inorganic fluoride containing vapors may also be used, such as, for example, hydrogen fluoride or even elemental fluorine gas.
The solid oxide compound can also be calcined at a temperature in a range of about 100 to about 900xc2x0 C. before being fluorided.
The amount of fluoride present before calcining is about 2 to about 50% by weight fluoride based on the weight of the fluorided solid oxide compound before calcining. Preferably, it is about 3 to about 25% by weight, and most preferably, it is 4 to 20% by weight fluoride based on the weight of the fluorided solid oxide compound before calcining.
It is important that the fluorided solid oxide compound be calcined. Generally, this calcining is conducted at a temperature in the range of about 200xc2x0 C. to about 900xc2x0 C., and for a time in the range of about 1 minute to about 100 hours. Preferably, the fluorided solid oxide compound is calcined at temperatures from about 300xc2x0 C. to about 700xc2x0 C. and a time in the range of about 1 hour to about 50 hours, most preferably, temperatures from 350xc2x0 C. to 600xc2x0 C. and a time in the range of 3 to 20 hours.
Calcining can be completed in any suitable atmosphere. Generally, the calcining is completed in an inert atmosphere. Alternatively, the calcining can be completed in an oxidizing atmosphere, such as, oxygen or air, or a reducing atmosphere, such as, hydrogen or carbon monoxide. Calcining can also be conducted in stages, for example, conducting the fluoriding in a gas phase at a lower temperature, then further calcining at a higher temperature. Alternatively, calcining can be conducted first in an oxidizing atmosphere, then in a reducing atmosphere at a different temperature, or vice-versa.
Optionally, a small amount of chloride can be included in or after the calcining treatment to achieve higher activity in some cases, or to increase the contribution of the titanium or zirconium.
The catalyst compositions of this invention can be produced by contacting the organometal compound, the organoaluminum compound, and the fluorided solid oxide compound, together. This contacting can occur in a variety of ways, such as, for example, blending. Furthermore, each of these compounds can be fed into a reactor separately, or various combinations of these compounds can be contacted together before being further contacted in the reactor, or all three compounds can be contacted together before being introduced into the reactor.
Currently, one method is to first contact the organometal compound and the fluorided solid oxide compound together, for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 15xc2x0 C. to 80xc2x0 C., to form a first mixture, and then contact this first mixture with an organoaluminum compound to form the catalyst composition.
Another method is to precontact the organometal compound, the organoaluminum compound, and the fluorided solid oxide compound before injection into a polymerization reactor for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 20xc2x0 C. to 80xc2x0 C.
A weight ratio of organoaluminum compound to the fluorided solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the fluorided solid oxide compound to the organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. The ratios are based on the amount of the components combined to give the catalyst composition.
After contacting, the catalyst composition comprises a post-contacted organometal compound, a post-contacted organoaluminum compound, and a post-contacted fluorided solid oxide compound. It should be noted that the post-contacted fluorided solid oxide compound is the majority, by weight, of the catalyst composition. Often times, specific components of a catalyst are not known, therefore, for this invention, the catalyst composition is described as comprising post-contacted compounds.
A weight ratio of the post-contacted organoaluminum compound to the post-contacted fluorided solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the post-contacted fluorided solid oxide compound to the post-contacted organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1.
The catalyst composition of this invention has an activity greater than a catalyst composition that uses the same organometal compound, and the same organoaluminum compound, but uses silica or titania that has been impregnated with fluoride as shown in comparative examples 4 and 5. This activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of about 50 to about 150xc2x0 C., and an ethylene pressure of about 400 to about 800 psig. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
However, it is preferred if the activity is greater than about 1000 grams of polymer per gram of fluorided solid oxide compound per hour, more preferably greater than 2000, and most preferably greater than 2,500. This activity is measured under slurry polymerization conditions, using isobutane as a diluent, and with a polymerization temperature of 90xc2x0 C., and an ethylene pressure of 550 psig. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
One of the important aspects of this invention is that no aluminoxane needs to be used in order to form the catalyst composition. Aluminoxane is an expensive compound that greatly increases polymer production costs. This also means that no water is needed to help form such aluminoxanes. This is beneficial because water can sometimes kill a polymerization process. Additionally, it should be noted that no borate compounds need to be used in order to form the catalyst composition. In summary, this means that the catalyst composition, which is heterogenous, and which can be used for polymerizing monomers or monomers and one or more comonomers, can be easily and inexpensively produced because of the absence of any aluminoxane compounds or borate compounds. Additionally, no organochromium compound needs to be added, nor any MgCl2 needs to be added to form the invention. Although aluminoxane, borate compounds, organochromium compounds, or MgCl2 are not needed in the preferred embodiments, these compounds can be used in other embodiments of this invention.
In another embodiment of this invention, a process comprising contacting at least one monomer and the catalyst composition to produce at least one polymer is provided. The term xe2x80x9cpolymerxe2x80x9d as used in this disclosure includes homopolymers and copolymers. The catalyst composition can be used to polymerize at least one monomer to produce a homopolymer or a copolymer. Usually, homopolymers are comprised of monomer residues, having 2 to about 20 carbon atoms per molecule, preferably 2 to about 10 carbon atoms per molecule. Currently, it is preferred when at least one monomer is selected from the group consisting of ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 3-ethyl-1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and mixtures thereof.
When a homopolymer is desired, it is most preferred to polymerize ethylene or propylene. When a copolymer is desired, the copolymer comprises monomer residues and one or more comonomer residues, each having from about 2 to about 20 carbon atoms per molecule. Suitable comonomers include, but are not limited to, aliphatic 1-olefins having from 3 to 20 carbon atoms per molecule, such as, for example, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, and other olefins and conjugated or nonconjugated diolefins such as 1,3-butadiene, isoprene, piperylene, 2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 1,7-hexadiene, and other such diolefins and mixtures thereof. When a copolymer is desired, it is preferred to polymerize ethylene and at least one comonomer selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. The amount of comonomer introduced into a reactor zone to produce a copolymer is generally from about 0.01 to about 10 weight percent comonomer based on the total weight of the monomer and comonomer, preferably, about 0.01 to about 5, and most preferably, 0.1 to 4. Alternatively, an amount sufficient to give the above described concentrations, by weight, in the copolymer produced can be used.
Processes that can polymerize at least one monomer to produce a polymer are known in the art, such as, for example, slurry polymerization, gas phase polymerization, and solution polymerization. It is preferred to perform a slurry polymerization in a loop reaction zone. Suitable diluents used in slurry polymerization are well known in the art and include hydrocarbons which are liquid under reaction conditions. The term xe2x80x9cdiluentxe2x80x9d as used in this disclosure does not necessarily mean an inert material; it is possible that a diluent can contribute to polymerization. Suitable hydrocarbons include, but are not limited to, cyclohexane, isobutane, n-butane, propane, n-pentane, isopentane, neopentane, and n-hexane. Furthermore, it is most preferred to use isobutane as the diluent in a slurry polymerization. Examples of such technology can be found in U.S. Pat. Nos. 4,424,341; 4,501,885; 4,613,484; 4,737,280; and 5,597,892; the entire disclosures of which are hereby incorporated by reference.
The catalyst compositions used in this process produce good quality polymer particles without substantially fouling the reactor. When the catalyst composition is to be used in a loop reactor zone under slurry polymerization conditions, it is preferred when the particle size of the solid oxide compound is in the range of about 10 to about 1000 microns, preferably about 25 to about 500 microns, and most preferably, 50 to 200 microns, for best control during polymerization.
In a specific embodiment of this invention, a process is provided to produce a catalyst composition, the process comprising (optionally, xe2x80x9cconsisting essentially ofxe2x80x9d, or xe2x80x9cconsisting ofxe2x80x9d):
(1) contacting a solid oxide compound with water containing ammonium bifluoride to produce a fluorided solid oxide compound;
wherein the solid oxide compound is selected from the group consisting of silica-titania and silica-zirconia;
(2) calcining the fluorided solid oxide compound at a temperature within a range of 350 to 600xc2x0 C. to produce a calcined composition having 4 to 20 weight percent fluoride based on the weight of the fluorided solid oxide compound before calcining;
(3) combining the calcined composition and bis(n-butylcyclopentadienyl) zirconium dichloride at a temperature within the range of 150xc2x0 C. to 80xc2x0 C. to produce a mixture; and
(4) after between 1 minute and 1 hour, combining the mixture and triethylaluminum to produce the catalyst composition.
Hydrogen can be used in this invention in a polymerization process to control polymer molecular weight.
One of the features of this invention is that the fluorided solid oxide compound activates the organometal compound much more efficiently than silica, silica-titania, or silica-zirconia alone. Thus, the titania or zirconia contributes to the activation of the organometal compound. A second feature of this invention is that the titania or zirconia is a weak polymerization catalyst in its own right, providing a high molecular weight component onto an otherwise symmetrical molecular weight distribution of the polymer produced by the organometal compound. This high molecular weight component, or skewed molecular weight distribution, imparts higher melt strength and shear response to the polymer than could be obtained from typical organometal compounds. These polymers may vary in molecular weight distribution depending on the organometal compound used and the relative contribution of the titanium or zirconium. One special feature of this invention, therefore, is that polydispersities of about 2.5 to about 4.0 and HLMI/MI values from about 25 to about 50 can be produced from organometal compounds that would otherwise give polydispersities of about 2.1 to about 2.5 and HLMI/MI values less than about 20.
After the polymers are produced, they can be formed into various articles, such as, for example, household containers and utensils, film products, drums, fuel tanks, pipes, geomembranes, and liners. Various processes can form these articles. Usually, additives and modifiers are added to the polymer in order to provide desired effects. It is believed that by using the invention described herein, articles can be produced at a lower cost, while maintaining most, if not all, of the unique properties of polymers produced with organometal compounds.